1. Field of the Invention
The present invention generally relates to an electronic display apparatus such as a projection display and a head mount display, and particularly to an image processing apparatus capable of dividing a single frame of image data into plural subframes of image data and combining the image data with OSD image data so as to provide a higher resolution display than the resolution of the image display device by time-division display, and an image display apparatus capable of displaying the above display.
2. Description of the Related Art
Recently, with the significant improvement in performance of information processing apparatuses, the resolution of the displayed images has been increasing. Accordingly, the demand of higher resolution in the image display apparatuses such as projectors has been increasing. As a method of increasing the resolution of images, there is a method where the image data of one frame is divided into plural subframes of image data, and the plural subframes are displayed by time-division display so as to provide a higher resolution than that of the image display device of the image display apparatus. Together with this, there is another demand that, in image display apparatuses such as projectors, previously stored data, such as tables, characters, and figures are often combined with the original image data to display the combined data upon, for example, an instruction of a user. The data, such as tables, characters, and figures, used to be combined with original image data are called OSD (On Screen Display) image data.
In the past, as an image processing method of not only dividing a single frame of image data into plural subframes of image data and displaying by time-division display to provide a higher resolution than that of the image display device but also combining the image data with OSD image data, there are, for example, an image processing method of combining original image data with OSD image data first, and dividing the combined image data into plural subframes, as described in Patent Document 1; and a method of dividing original image data into plural subframes, and followed by performing image processing, as described in Patent Document 2.    Patent Document 1: Japanese Patent Application Publication No. 2003-302952.    Patent Document 2: Japanese Patent Application Publication No. 2005-189546.
However, in the method of the Patent Document 1, since the amount of display image data to be image-processed will be increased as the resolution is increased, a very fast processing performance will be required to achieve real-time image processing, thereby causing a case where real-time image processing cannot be achieved. Even when such a very fast processing performance is achieved, the cost of parts required to achieve such high performance is expensive, thereby disadvantageously increasing the cost of the entire apparatus. On the other hand, in the method of the Patent Document 2, a higher processing performance is partially achieved by providing the same number of units as the number of subframes for some of the units to perform OSD processing in parallel. However, in a process in which data are loaded from the storage unit to the load storage unit, since the pixel data of the OSD data are transferred one by one, the processing performance in this process will not be increased, and the same problems as in the method according to Patent Document 1 occurs as the resolution of the images is increased.